Composting cow manure + water hyacinth + fish & meat wastes
"Water hyacinth, cow dung and cow urine have long been used as manure.
But Mr Iyengara has also developed organic manure from fish waste,
"charasuda" (butcher house waste), "indsafari" (small fish) and the
"bhasmas" (made from herbs and metals)."
Sounds like they have large quantities of raw materials for compost
making. If they harvest lots of large water hyacinth that means
the water they were growing in was nutrient rich. I think a site plan
could be designed for a farm or farming community that involved keeping
livestock on open land with lots of forage and a manure collection
system for the compost making operation; water runoff (probably nutrient
rich) could be channeled into aquaculture ponds for growing hyacinth,
duckweed and food fish.